Budworm trapping

Native budworm (Helicoverpa punctigera) 1st instar larvae have been identified in the Mid North, in lentils at Locheil and peas at Telowie. High levels of moth activity have been observed in many legume crops across the Mid North. On upper Eyre Peninsula, 1st instar larvae have been collected during sweep netting of a number of crops of peas, vetch and lupins. University of New England Researcher, Peter Gregg, has recently observed high populations of native budworm and lesser budworm (Heliothis punctifera) during sweep net surveys of native hosts in northern South Australia and southwest Queensland. Peter believes these population levels create potential for above average populations in cropping areas this spring.

The latest counts of native budworm moths captured in the trapping network indicate the occurrence of moderate to high moth flights around the Cleve-Kimba-Pinkawillinie, and Port Broughton - Mannanarie areas, with light activity elsewhere (see table below). These figures indicate that numbers are increasing on upper Eyre Peninsula and in the Mid North; there was a flight on upper Yorke Peninsula during the week ending 31st August, and significant flights on upper Eyre Peninsula on 1st September, and in the Mid North on 6th September.

Modelling of native budworm development (thanks to Dr. Garry McDonald, cesar, University of Melbourne) currentlypredicts that 3rd instar larvae could be found in crops around the 10th October, and the most damaging 5th instars on 13th - 20th October. To avoid 5th instar damage, it is advisable to time appropriate insecticide treatments when 3rd instars first appear.

Native budworm moth counts from seven trap locations are:

Region

Location

Date

H. punctigera

H. armigera

Fleurieu Peninsula

Milang

15/08/2016

0

0

Milang

30/08/2016

0

0

Yorke Peninsula

Port Broughton

31/08/2016

209

0

Port Broughton

5/09/2016

28

1

Eyre Peninsula

Cleve

29/08/2016

167

6

Cleve

2/09/2016

165

6

Pinkawillinie

26/08/2016

64

3

Cummins

25/08/2016

0

1

Kimba

1/09/2016

250

3

South East

Frances

23/08/2016

1

0

Frances

30/08/2016

2

0

Frances

6/09/2016

14

0

Mid North

Mannanarie

23/08/2016

18

4

Mannanarie

30/08/2016

151

48

Mannanarie

6/09/2016

343

120

Monitor crops by taking multiples of ten sweeps in representative locations across the paddock and calculate the average number of larvae per 10 sweeps. An economic threshold calculator for direct yield loss (not grain quality), developed by DAFWA, is demonstrated in the PestNotes Southern fact sheet (link below). Growers should substitute in their own control costs and grain prices. Research by QDAF has shown that, under current cost structures, spray decisions in smaller seeded pulse crops (e.g. desi chickpea) can be made based on these calculated yield loss thresholds without risking penalties for reduced grain quality; however, this may not apply to larger seeded grains (e.g. Faba bean, field pea) where there is a higher likelihood of unacceptable levels of partially chewed grain in the sample. If treatment is warranted, one well-timed synthetic pyrethroid application often provides effective control and may prevent reinfestation for up to six weeks.

Further updates of trapping results will appear in future issues of PestFacts newsletters.